Delirium (Latin deliro, to go out of the way: de, away; lira, a furrow). Hobbes defines delirium to be "too much appearing passion." Madness may be said to be habitual delirium, and delirium may be regarded as a temporary madness. The popular equivalent for the term delirium is light-headedness. Delirium is often associated with fever, and may then be due to disease of the brain (e.g. meningitis), or be symptomatic of one of the specific fevers (typhus, typhoid, smallpox, etc.). Or delirium may be unassociated with fever, as in poisoning by belladonna or alcohol, in certain forms of chronic disease, and in dying people. The treatment of delirium is largely dependent on its cause. The main indication is to procure sleep ; the local application of cold to the head is often of considerable service.